Blood is composed of a variety of elements. Approximately 45% of blood volume is composed of red cells (erythrocytes), white cells (leukocytes) and platelets. The acellular element of plasma makes up the remaining portion of blood of which approximately 90% is water. The remaining portion comprises proteins, antibodies, antigens, imune complexes, pathogens, toxins and other various organic and inorganic matter.
During surgical operations an extracorporeal circuit is frequently employed for a variety of purposes such as in the use of a heart-lunq machine. The blood is delivered to the circuit outside the body, or "extracorporeally." Such a circuit allows the surgeon to provide life sustaining treatment through the blood while performing surgery. As it is known, a large amount of fluid is needed to prime and operate such a circuit, said fluid comprising the patient blood as well as additional water to make up for volume of the circuit flow passageways.
During certain surgical procedures an anti-coagulant such as heparin is introduced into the extracorporeal circuit to prevent the blood from clotting while it is outside the patient. The situation then arises where the plasma is "contaminated" by the heparin, for it cannot be infused into the patient as large dosages of heparin will prevent the patient's blood from its natural coagulation by impeding the patients blood from performing its natural clotting ability. For this reason the red blood cells (erythrocytes) are separated from the plasma, and the whole blood re-infused into the patient, allowing the patient to maintain a portion of his own cellular blood components while the plasma is discarded. Commensurate with the loss of plasma is the loss of blood proteins having the highly desired clotting factors.
The major disadvantage of this procedure is that the loss of plasma reduces the patients' ability to heal or result in hemorrhaging, especially in a patient who has completed cardiopulmonary bypass. This most critical of patients is infused under current procedure, with only a portion of his own whole blood because the remaining blood volume, which was once the patient's own plasma, is lost.
Further aggravating the situation, donor plasma may be needed to increase a patient's blood volume, which comes from unknown, and possibly undesirable, donors. Problems include the need to screen donor plasma for pathogens such as the immune deficiency virus ("HIV") which can cause the acquired immune deficiency syndrome ("AIDS"). Further, problems can exist in depleting the patient's body of a naturally developed balance of blood that cannot be duplicated in a laboratory. This balance can speed the recovery process of the patient and possibly prevent shock from occurring due to the donor plasma which is foreign to the patient's body.
In furtherance of the problems associated with the use of donor plasma is the fact that there is a limited supply and that supply can be cut short by reason of contamination, other emergencies, or simply that a particular patient needs a rare type of plasma.
The problems described are those which plague the use of extracorporeal circuits and the associated reuse of blood. While steps have been made toward effectively and simply resolving these problems, no satisfactory solution has heretofore been provided. My method and apparatus is specifically designed to overcome the aforementioned problems. It is, therefore, to the effective resolution of these problems that the present invention is directed.